I have a lot of directories:
13R
613
AB1
ACT
AMB
ANI
Each directories contains a lots of file:
20140828.13R.file.csv.gz
20140829.13R.file.csv.gz
20140830.13R.file.csv.gz
20140831.13R.file.csv.gz
20140901.13R.file.csv.gz
20131114.613.file.csv.gz
20131115.613.file.csv.gz
20131116.613.file.csv.gz
20131117.613.file.csv.gz
20141114.ab1.file.csv.gz
20141115.ab1.file.csv.gz
20141116.ab1.file.csv.gz
20141117.ab1.file.csv.gz
etc..
The purpose if to have the first file from each directories
The result what I expect is:
13R|20140828
613|20131114
AB1|20141114
Which is the name of the directories pipe the date from the filename.
I guess I need a find and head command + awk but I can't make it, I need your help.
Here what I have test it
for f in $(ls -1);do ls -1 $f/ | head -1;done
But the folder name is missing.
When I mean the first file, is the first file returned in an alphabetical order within the folder.
Thanks.
You can do this with a Bash loop.
Given:
/tmp/test
/tmp/test/dir_1
/tmp/test/dir_1/file_1
/tmp/test/dir_1/file_2
/tmp/test/dir_1/file_3
/tmp/test/dir_2
/tmp/test/dir_2/file_1
/tmp/test/dir_2/file_2
/tmp/test/dir_2/file_3
/tmp/test/dir_3
/tmp/test/dir_3/file_1
/tmp/test/dir_3/file_2
/tmp/test/dir_3/file_3
/tmp/test/file_1
/tmp/test/file_2
/tmp/test/file_3
Just loop through the directories and form an array from a glob and grab the first one:
prefix="/tmp/test"
cd "$prefix"
for fn in dir_*; do
cd "$prefix"/"$fn"
arr=(*)
echo "$fn|${arr[0]}"
done
Prints:
dir_1|file_1
dir_2|file_1
dir_3|file_1
If your definition of 'first' is different that Bash's, just sort the array arr according to your definition before taking the first element.
You can also do this with find and awk:
$ find /tmp/test -mindepth 2 -print0 | awk -v RS="\0" '{s=$0; sub(/[^/]+$/,"",s); if (s in paths) next; paths[s]; print $0}'
/tmp/test/dir_1/file_1
/tmp/test/dir_2/file_1
/tmp/test/dir_3/file_1
And insert a sort (or use gawk) to sort as desired
sort has an unique option. Only the directory should be unique, so use the first field in sorting -k1,1. The solution works when the list of files is sorted already.
printf "%s\n" */* | sort -k1,1 -t/ -u | sed 's#\(.*\)/\([0-9]*\).*#\1|\2#'
You will need to change the sed command when the date field may be followed by another number.
This works for me:
for dir in $(find "$FOLDER" -type d); do
FILE=$(ls -1 -p $dir | grep -v / | head -n1)
if [ ! -z "$FILE" ]; then
echo "$dir/$FILE"
fi
done
Related
This question already has answers here:
Linux Command Line using for loop and formatting results
(3 answers)
Closed 5 years ago.
I want to create a bash script that searches a given directory for pictures to copy. the pictures have to have the name format IMG_\d\d\d\d.JPG. If the pictures have a duplicate filename, then copy them to /images/archives and append .JPG to the end of their name, so the duplicates have .JPG.JPG. There are also duplicate pictures, so I want to hash each picture and check if it is a duplicate picture. If it is a duplicate picture, then do not copy the duplicate into /archives but store the duplicate file path into a file called output.txt.
I am struggling with trying to get the duplicate hashes to display the filenames as well. This is what I had so far:
if [ -d $1 ]
then echo using directory $1 as source
else echo Sorry, not a valid drive
exit
fi
if [ -d $2 ]
then echo $2 target location already exists
else mkdir -p $2
fi
cd $1
myList=`find . -mindepth 1 -type f -name "*MG_[0-9][0-9][0-9][0-9].JPG"`
echo $myList
ImagesToCopy=`find . -mindepth 1 -type f -name "*MG_[0-9][0-9][0-9][0-9].JPG" -exec md5sum {} \; | cut -f1 -d" " | sort | uniq`
echo $ImagesToCopy
This gives me a list of the files I need to copy and their hashes. In the command line if I type in the command:
# find . -mindepth 1 -type f -name "*MG_[0-9][0-9][0-9][0-9].JPG" -exec md5sum {} \; | sort | cut -f1 -d" "| uniq -d
I receive the results:
266ab54fd8a6dbc7ba61a0ee526763e5
88761da2c2a0e57d8aab5327a1bb82a9
cc640e50f69020dd5d2d4600e20524ac
This is the list of duplicate files that I do not want to copy but I want to also display the file path and filenames alongside this, like this:
# find . -mindepth 1 -type f -name "*MG_[0-9][0-9][0-9][0-9].JPG" -exec md5sum {} \; | sort -k1 | uniq -u
043007387f39f19b3418fcba67b8efda ./IMG_1597.JPG
05f0c10c49983f8cde37d65ee5790a9f ./images/IMG_2012/IMG_2102.JPG
077c22bed5e0d0fba9e666064105dc72 ./DCIM/IMG_0042.JPG
1a2764a21238aaa1e28ea6325cbf00c2 ./images/IMG_2012/IMG_1403.JPG
1e343279cd05e8dbf371331314e3a2f6 ./images/IMG_1959.JPG
2226e652bf5e3ca3fbc63f3ac169c58b ./images/IMG_0058.JPG
266ab54fd8a6dbc7ba61a0ee526763e5 ./images/IMG_0079.JPG
266ab54fd8a6dbc7ba61a0ee526763e5 ./images/IMG_2012/IMG_0079.JPG
2816dbcff1caf70aecdbeb934897fd6e ./images/IMG_1233.JPG
451110cc2aff1531e64f441d253b7fec ./DCIM/103canon/IMG_0039.JPG
45a00293c0837f10e9ec2bfd96edde9f ./DCIM/103canon/IMG_0097.JPG
486f9dd9ee20ba201f0fd9a23c8e7289 ./images/IMG_2013/IMG_0060.JPG
4c2054c57a2ca71d65f92caf49721b4e ./DCIM/IMG_1810.JPG
53313e144725be3993b1d208c7064ef6 ./IMG_2288.JPG
5ac56dcddd7e0fd464f9b243213770f5 ./images/IMG_2012/favs/IMG_0039.JPG
65b15ebd20655fae29f0d2cf98588fc3 ./DCIM/IMG_2564.JPG
88761da2c2a0e57d8aab5327a1bb82a9 ./images/IMG_2012/favs/IMG_1729.JPG
88761da2c2a0e57d8aab5327a1bb82a9 ./images/IMG_2013/IMG_1729.JPG
8fc75b0dd2806d5b4b2545aa89618eb6 ./DCIM/103canon/IMG_2317.JPG
971f0a4a064bb1a2517af6c058dc3eb3 ./images/IMG_2012/favs/IMG_2317.JPG
aad617065e46f97d97bd79d72708ec10 ./images/IMG_2013/IMG_1311.JPG
c937509b5deaaee62db0bf137bc77366 ./DCIM/IMG_1152.JPG
cc640e50f69020dd5d2d4600e20524ac ./images/IMG_2012/favs/IMG_2013.JPG
cc640e50f69020dd5d2d4600e20524ac ./images/IMG_2013/IMG_2013.JPG
d8edfcc3f9f322ae5193e14b5f645368 ./images/IMG_2012/favs/IMG_1060.JPG
dcc1da7daeb8507f798e4017149356c5 ./DCIM/103canon/IMG_1600.JPG
ded2f32c88796f40f080907d7402eb44 ./IMG_0085.JPG
Thanks in advance.
Let's suppose that you have the results of md5sum. For example:
$ cat file
266ab54fd8a6dbc7ba61a0ee526763e5 /path/to/file1a
88761da2c2a0e57d8aab5327a1bb82a9 /path/to/file2a
266ab54fd8a6dbc7ba61a0ee526763e5 /path/to/file1b
cc640e50f69020dd5d2d4600e20524ac /path/to/file3
88761da2c2a0e57d8aab5327a1bb82a9 /path/to/file2b
To remove duplicates from the list, use awk:
$ awk '!($1 in a){a[$1]; print}' file
266ab54fd8a6dbc7ba61a0ee526763e5 /path/to/file1a
88761da2c2a0e57d8aab5327a1bb82a9 /path/to/file2a
cc640e50f69020dd5d2d4600e20524ac /path/to/file3
This uses the array a to keep track of which md5 sums we have seen so far. For each line, if the md5 has not appeared before, !($1 in a), we mark that md5 as having been seen and print the line.
Alternative
A shorter version of the code is:
$ awk '!a[$1]++' file
266ab54fd8a6dbc7ba61a0ee526763e5 /path/to/file1a
88761da2c2a0e57d8aab5327a1bb82a9 /path/to/file2a
cc640e50f69020dd5d2d4600e20524ac /path/to/file3
This uses array a to count the number of times that md5sum $1 has appeared. If the count is initially zero, then the line is printed.
I need to find the latest file - filename_YYYYMMDD in the directory DIR.
The below is not working as the position is shifting each time because of the spaces between(occurring mostly at file size field as it differs every time.)
please suggest if there is other way.
report =‘ls -ltr $DIR/filename_* 2>/dev/null | tail -1 | cut -d “ “ -f9’
You can use AWK to cut the last field . like below
report=`ls -ltr $DIR/filename_* 2>/dev/null | tail -1 | awk '{print $NF}'`
Cut may not be an option here
If I understand you want to loop though each file in the directory and file the largest 'YYYYMMDD' value and the filename associated with that value, you can use simple POSIX parameter expansion with substring removal to isolate the 'YYYYMMDD' and compare against a value initialized to zero updating the latest variable to hold the largest 'YYYYMMDD' as you loop over all files in the directory. You can store the name of the file each time you find a larger 'YYYYMMDD'.
For example, you could do something like:
#!/bin/sh
name=
latest=0
for i in *; do
test "${i##*_}" -gt "$latest" && { latest="${i##*_}"; name="$i"; }
done
printf "%s\n" "$name"
Example Directory
$ ls -1rt
filename_20120615
filename_20120612
filename_20120115
filename_20120112
filename_20110615
filename_20110612
filename_20110115
filename_20110112
filename_20100615
filename_20100612
filename_20100115
filename_20100112
Example Use/Output
$ name=; latest=0; \
> for i in *; do \
> test "${i##*_}" -gt "$latest" && { latest="${i##*_}"; name="$i"; }; \
> done; \
> printf "%s\n" "$name"
filename_20120615
Where the script selects filename_20120615 as the file with the greatest 'YYYYMMDD' of all files in the directory.
Since you are using only tools provided by the shell itself, it doesn't need to spawn subshells for each pipe or utility it calls.
Give it a test and let me know if that is what you intended, let me know if your intent was different, or if you have any further questions.
I have a directory, ./grd_files/lat36/ that has 7 files in it (n36e114.grd, n36e115.grd, n36e116.grd, n36e117.grd, n36e118.grd, n36e119.grd, n36e120.grd. Also beneath ./grd_files/ are other folders named lat37, lat38, lat39. Each contains some files named in the same format as those in lat36, only instead of n36e114.grd, the file for the e114 longitude in the lat37 folder would be called n37e114. Now, not all lat** folders contain all the longitudes, but I need them to.
I have written a part of the script to determine which lat** folder has the most columns in it (it is lat36 with 7 longitudes). I want to compare the longitudes that exist in lat36 folder to the other folders, and if a column is missing in another folder, I will make it. I can handle the if then statement, but I am stumped on how to compare the lists in bash.
I was thinking to make a list of the file names in the row1 folder, and compare that to the to the files in the other folders, but the names won't and shouldn't match -- only the column part of the name will and should match. So far I have tried to make an array of the file names and then parse it for just the column part of the name. Note that these are actually map tiles, so the names are really in the format of coordinates in northing (row) and easing (col) e.g. n36e114.grd. So I want to isolate all the e114 style parts of the names and check and make sure that they exist in the other rows. I hope that makes sense. Below is what I attempted, but I am not great in bash syntax so I'm stumped. Thanks so much for the help.
col_list_raw=( $(find $maxdirectory -name ".grd" -exec basename {} .grd \;) )
col_list=( for c in ${col_list_raw[#]}; do echo ${col_list_raw[$c]:3:7}; done )
where $maxdirectory is the one with the most columns.*
UPDATE: I have removed what I described in italics above and attempted to incorporate the solution from John1024. Below is the code.
cd ./grd_files
for row in lat*/
do
ls "$row" | sed 's/.*lon/lon/' >"${row%/}.tmp"
done
for f in lat*.tmp
do
grep -vFf "$f" ${latXX}.tmp >missing.tmp
[ -s missing.tmp ] && echo ${f%.tmp} is missing $(cat missing.tmp)
done
cd ..
Where latXX is the folder with the most longitudes. John1024's first loop works nicely, and I get the correct lists for each of the lat** folders, but the second loop straight up compares the lists , returning:
lat37 is missing n36e114.grd n36e115.grd n36e116.grd n36e117.grd n36e118.grd n36e119.grd n36e120.grd
lat38 is missing n36e114.grd n36e115.grd n36e116.grd n36e117.grd n36e118.grd n36e119.grd n36e120.grd
lat39 is missing n36e114.grd n36e115.grd n36e116.grd n36e117.grd n36e118.grd n36e119.grd n36e120.grd
I need that loop to compare only part of the file name. ie I want to check each folder for the existence of each longitude. So that if file `n37e114.grd' exists, nothing happens, but if it does not exist, that information is returned and I can execute a command based on the missing file. I hope my edits clear up the naming convention and are understandable. Thanks again for the help. AM
SOLUTION:
thanks to the help of #John1024 I was able to find a solution. I have reproduced the final solution below. Following this, I read in the *.out files and conduct my command on each line of them.
cd ./grd_files
for lat in */
do
ls "$lat" | sed 's/[a-z][1-9][1-9].*\([a-z][0-9][0-9]*\).grd/\1/' >"${lat%/}.tmp"
done
for file in *.tmp
do
lat=$(echo $file | awk -F "." '{print $1}')
grep -vFf "$file" ${xXX}.tmp >${lat}missing.out
[ -s ${lat}missing.out ] && echo ${file%.tmp} is missing $(cat ${lat}missing.out)
done
The question includes two different naming schemes for the files. Both would work the same, but to keep it simple and intuitive, this answer uses the first scheme.
It is possible to loop through bash arrays to find the missing columns. However, grep is well-suited to this task, greatly simplifies the logic, and, if there are many columns and rows, it is likely much faster. Using grep:
cd ./grd_files
for row in row*/
do
ls "$row" | sed 's/.*col/col/' >"${row%/}.tmp"
done
for f in row*.tmp
do
grep -vFf "$f" row1.tmp >missing.tmp
[ -s missing.tmp ] && echo ${f%.tmp} is missing $(cat missing.tmp)
done
The first loop above, creates lists of columns that exist in each of the rows. These lists are saved in temporary files name row1.tmp, row2.tmp, etc.
The second loop compares each of those lists to the reference row, row1.tmp. The list of columns missing from that row are saved in temporary file missing.tmp. If missing.tmp has a nonzero size, then there are missing columns and a report is generated.
For cleanup, one might want to delete the tmp files. If so, add this line to the end of the script:
rm row*.tmp missing.tmp
Fancier version
Using process substitution, the need for many of the temporary files can be eliminated:
trap "rm missing.tmp" EXIT
for row in row*/
do
ls row1/ | sed 's/.*col/col/' | grep -vFf <(ls "$row" | sed 's/.*col/col/') >missing.tmp
[ -s missing.tmp ] && echo $row is missing $(cat missing.tmp)
done
This version also uses trap to assure that the sole remaining temporary file is removed when the script is finished.
Using the other naming scheme as per revised question
cd ./grd_files
for row in lat*/
do
ls "$row" | sed 's/.*n[0-9][0-9]e/e/' >"${row%/}.tmp"
done
for f in lat*.tmp
do
grep -vFf "$f" ${latXX}.tmp >missing.tmp
[ -s missing.tmp ] && echo ${f%.tmp} is missing $(cat missing.tmp)
done
cd ..
As I told you in the comment, supplying the test data is a good practice. In this case you would got much more answers if supplied a script what creating a test case, something such next:
mkdir grid
cd grid
mkdir lat3{5..9}
#if you don't know the {3..9} expansion, simply write
#mkdir lat36 lat37 lat38 lat39
touch lat35/n35e111.grd
touch lat36/n36e11{4..9}.grd lat36/n36e120.grd
touch lat37/n37e11{4,6,8}.grd
touch lat38/n38e11{4..9}.grd
#39 missing all files
Such script what creating an test case helps much more as full page of words. ;) Or, if no script, at least supply the output of find like find grid -print. Your first edit helps a bit, (I missed it) and +100 to #John1024's work.
Now about the solution.
Your final solution have one problem. What if the directory with the MOST LONGITUDES (your latXX) missing some gridfile what exists in some other directories? E.g. it has the most gridfiles, but still not all. Like in the above test case, the lat36 contains 7 files (most of all), but sill missing a file n36e111.grd (because the 111 exists only in the lat35)?
Therefore i created an alternative solution, what eliminates this problem and show the result as the next matrix:
111 114 115 116 117 118 119 120
35: + no no no no no no no # the 111 is here
36: no + + + + + + + # the dir with a MOST of longitudes but missing 111
37: no + no + no + no no
38: no + + + + + + no
39: no no no no no no no no # missing all longitudes
the script
start="./test/grid"
cd "$start" || err "can cd to $start" || exit 1
known_longs=$(find . -type f -name \*.grd -print | sed 's:.*/n.*e\([0-9][0-9]*\)\.grd:\1:' | sort -u)
known_lats=$(find . -type d -print | grep -oP 'lat\K\d+(?=/?)' | sort -u)
print_matrix() {
echo -ne "\t"
paste -s - <<<"$known_longs"
for lat in $known_lats
do
echo -en "$lat:"
for long in $known_longs
do
[[ -e "./lat${lat}/n${lat}e${long}.grd" ]] && echo -en "\t+" || echo -en "\tno"
done
echo
done
}
print_matrix
The logic is easy:
search for all known longs e.g. for the filenames what contains eNNN
search for all known lats e.g. for the directories wit latNN
in a cycle test the existence if the files
The above printed matrix is probably not very useful, because you probably want do something with the found or missing files, so here is an action variant of the script.
start="./test/grid"
cd "$start" || err "can cd to $start" || exit 1
known_longs=$(find . -type f -name \*.grd -print | sed 's:.*/n.*e\([0-9][0-9]*\)\.grd:\1:' | sort -u)
known_lats=$(find . -type d -print | grep -oP 'lat\K\d+(?=/?)' | sort -u)
do_if_exists() {
local xlat="$1"
local xlong="$2"
filename="n${xlat}e${xlong}.grd"
#do nothing
}
do_if_missing() {
local xlat="$1"
local xlong="$2"
filename="n${xlat}e${xlong}.grd"
echo "from lat$xlat missing $filename"
}
do_actions() {
for lat in $known_lats
do
for long in $known_longs
do
[[ -e "./lat${lat}/n${lat}e${long}.grd" ]] && do_if_exists $lat $long || do_if_missing $lat $long
done
done
}
do_actions
what for the missing file do an action (echoes what missing), and the output is the next:
from lat35 missing n35e114.grd
from lat35 missing n35e115.grd
from lat35 missing n35e116.grd
from lat35 missing n35e117.grd
from lat35 missing n35e118.grd
from lat35 missing n35e119.grd
from lat35 missing n35e120.grd
from lat36 missing n36e111.grd
from lat37 missing n37e111.grd
from lat37 missing n37e115.grd
from lat37 missing n37e117.grd
from lat37 missing n37e119.grd
from lat37 missing n37e120.grd
from lat38 missing n38e111.grd
from lat38 missing n38e120.grd
from lat39 missing n39e111.grd
from lat39 missing n39e114.grd
from lat39 missing n39e115.grd
from lat39 missing n39e116.grd
from lat39 missing n39e117.grd
from lat39 missing n39e118.grd
from lat39 missing n39e119.grd
from lat39 missing n39e120.grd
Of course, is possible optimise more, like:
do the find only once (helps if the directory tree is large - by creating a list of filenames by the find command
don't test each file, but test the existence of the filename in the previously created list of filenames
like in the next
startdir="./test/grid"
(cd "$startdir" || err "can cd to $start" || exit 1
gridlist="/tmp/griglist.$$"
trap "rm -f $gridlist;exit" 0 2
find . -regex '\./lat[0-9][0-9]*.*' -print >$gridlist
known_longs=($(sed -n 's:^.*/n[0-9][0-9]*e\([0-9][0-9]*\)\.grd$:\1:p' $gridlist | sort -u))
known_lats=($(grep -oP '/lat\K\d+((?=/?)|$)' $gridlist | sort -u))
full_list() {
for lat in ${known_lats[#]}
do
for long in ${known_longs[#]}
do
echo "./lat${lat}/n${lat}e${long}.grd"
done
done
}
comm -13 $gridlist <(full_list)) | while read missing
do
#do something with the miising file
echo "$missing"
done
I think of xargs as the map function of the UNIX shell. What is the filter function?
EDIT: it looks like I'll have to be a bit more explicit.
Let's say I have to hand a program which accepts a single string as a parameter and returns with an exit code of 0 or 1. This program will act as a predicate over the strings that it accepts.
For example, I might decide to interpret the string parameter as a filepath, and define the predicate to be "does this file exist". In this case, the program could be test -f, which, given a string, exits with 0 if the file exists, and 1 otherwise.
I also have to hand a stream of strings. For example, I might have a file ~/paths containing
/etc/apache2/apache2.conf
/foo/bar/baz
/etc/hosts
Now, I want to create a new file, ~/existing_paths, containing only those paths that exist on my filesystem. In my case, that would be
/etc/apache2/apache2.conf
/etc/hosts
I want to do this by reading in the ~/paths file, filtering those lines by the predicate test -f, and writing the output to ~/existing_paths. By analogy with xargs, this would look like:
cat ~/paths | xfilter test -f > ~/existing_paths
It is the hypothesized program xfilter that I am looking for:
xfilter COMMAND [ARG]...
Which, for each line L of its standard input, will call COMMAND [ARG]... L, and if the exit code is 0, it prints L, else it prints nothing.
To be clear, I am not looking for:
a way to filter a list of filepaths by existence. That was a specific example.
how to write such a program. I can do that.
I am looking for either:
a pre-existing implementation, like xargs, or
a clear explanation of why this doesn't exist
If map is xargs, filter is... still xargs.
Example: list files in the current directory and filter out non-executable files:
ls | xargs -I{} sh -c "test -x '{}' && echo '{}'"
This could be made handy trough a (non production-ready) function:
xfilter() {
xargs -I{} sh -c "$* '{}' && echo '{}'"
}
ls | xfilter test -x
Alternatively, you could use a parallel filter implementation via GNU Parallel:
ls | parallel "test -x '{}' && echo '{}'"
So, youre looking for the:
reduce( compare( filter( map(.. list()) ) ) )
what can be rewiritten as
list | map | filter | compare | reduce
The main power of bash is a pipelining, therefore isn't need to have one special filter and/or reduce command. In fact nearly all unix commands could act in one (or more) functions as:
list
map
filter
reduce
Imagine:
find mydir -type f -print | xargs grep -H '^[0-9]*$' | cut -d: -f 2 | sort -nr | head -1
^------list+filter------^ ^--------map-----------^ ^--filter--^ ^compare^ ^reduce^
Creating a test case:
mkdir ./testcase
cd ./testcase || exit 1
for i in {1..10}
do
strings -1 < /dev/random | head -1000 > file.$i.txt
done
mkdir emptydir
You will get a directory named testcase and in this directory 10 files and one directory
emptydir file.1.txt file.10.txt file.2.txt file.3.txt file.4.txt file.5.txt file.6.txt file.7.txt file.8.txt file.9.txt
each file contains 1000 lines of random strings some lines are contains only numbers
now run the command
find testcase -type f -print | xargs grep -H '^[0-9]*$' | cut -d: -f 2 | sort -nr | head -1
and you will get the largest number-only line from each files like: 42. (of course, this can be done more effectively, this is only for demo)
decomposed:
The find testcase -type f -print will print every plain files so, LIST (and reduced only to files). ouput:
testcase/file.1.txt
testcase/file.10.txt
testcase/file.2.txt
testcase/file.3.txt
testcase/file.4.txt
testcase/file.5.txt
testcase/file.6.txt
testcase/file.7.txt
testcase/file.8.txt
testcase/file.9.txt
the xargs grep -H '^[0-9]*$' as MAP will run a grep command for each file from a list. The grep is usually using as filter, e.g: command | grep, but now (with xargs) changes the input (filenames) to (lines containing only digits). Output, many lines like:
testcase/file.1.txt:1
testcase/file.1.txt:8
....
testcase/file.9.txt:4
testcase/file.9.txt:5
structure of lines: filename colon number, want only numbers so calling a pure filter, what strips out the filenames from each line cut -d: -f2. It outputs many lines like:
1
8
...
4
5
Now the reduce (getting the largest number), the sort -nr sorts all number numerically and reverse order (desc), so its output is like:
42
18
9
9
...
0
0
and the head -1 print the first line (the largest number).
Of course, you can write your own list/filter/map/reduce functions directly with bash programming constructions (loops, conditions and such), or you can employ any fullblown scripting language like perl, special languages like awk, sed "language", or dc (rpn) and such.
Having an special filter command such:
list | filter_command cut -d: -f 2
is simple doesn't needed, because you can use directly the
list | cut
You can have awk do the filter and reduce function.
Filter:
awk 'NR % 2 { $0 = $0 " [EVEN]" } 1'
Reduce:
awk '{ p = p + $0 } END { print p }'
I totally understand your question here as a long time functional programmer and here is the answer: Bash/unix command pipelining isn't as clean as you'd hoped.
In the example above:
find mydir -type f -print | xargs grep -H '^[0-9]*$' | cut -d: -f 2 | sort -nr | head -1
^------list+filter------^ ^--------map-----------^ ^--filter--^ ^compare^ ^reduce^
a more pure form would look like:
find mydir | xargs -L 1 bash -c 'test -f $1 && echo $1' _ | grep -H '^[0-9]*$' | cut -d: -f 2 | sort -nr | head -1
^---list--^^-------filter---------------------------------^^------map----------^^--map-------^ ^reduce^
But, for example, grep also has a filtering capability: grep -q mypattern which simply return 0 if it matches the pattern.
To get a something more like what you want, you simply would have to define a filter bash function and make sure to export it so it was compatible with xargs
But then you get into some problems. Like, test has binary and unary operators. How will your filter function handle this? Hand, what would you decide to output on true for these cases? Not insurmountable, but weird. Assuming only unary operations:
filter(){
while read -r LINE || [[ -n "${LINE}" ]]; do
eval "[[ ${LINE} $1 ]]" 2> /dev/null && echo "$LINE"
done
}
so you could do something like
seq 1 10 | filter "> 4"
5
6
7
8
9
As I wrote this I kinda liked it
I need to determine if there are any directory names > 31 characters in a given directory (i.e. look underneath that root).
I know I can use something like find /path/to/root/dir -type d >> dirnames.txt
This will give me a text file of complete paths.
What I need is to get the actual number of characters in each directory name. Not sure if parsing the above results w/sed or awk makes sense. Looking for ideas/thoughts/suggestions/tips on how to accomplish this. Thanks!
This short script does it all in one go, i.e. finds all directory names and then outputs any which are greater than 31 characters in length (along with their length in characters):
for d in `find /path/to/root/dir -type d -exec basename {} \;` ; do
len=$(echo $d | wc -c)
if [ $len -gt 31 ] ; then
echo "$d = $len characters"
fi
done
Using your dirnames.txt file created by your find cmd, you can then sort the data by length of pathname, i.e.
awk '{print length($0) "\t" $0}' dirnames.txt | sort +0nr -1 > dirNamesWithSize.txt
This will present the longest path names (based on the value of length) at the top of the file.
I hope this helps.
Try this
find . -type d -exec bash -c '[ $(wc -c <<<"${1##*/}") -gt 32 ] && echo "${1}"' -- {} \; 2>/dev/null
The one bug, which I consider minor, is that it will over-count directory name length by 1 every time.
If what you wanted was the whole path rather than the last path component, then use this:
find . -type d | sed -e '/.\{32,\}/!d'
This version also has a bug, but only when file names have embedded newlines.
The output of both commands is a list of file names which match the criteria. Counting the length of each one is trivial from there.